Time train of a timepiece of the stem-setting type



Dec. 21, 1954 P. H. MORGANSON 2,697,324

TIME TRAIN OF A TIMEPIECE OF THE STEM-SETTING TYPE Filed Jan. 22, 1953 /4 F? 31 I: V

72 T- 2a 5i 22 24 M 44 42 40 J6 45 /e fjer AO /0 00600 United States Patent TIME TRAIN OF A TIMEPIECE OF THE STEM-SETTING TYPE Peter H. Morganson, Winsted, C0nn., assignor to The William L. Gilbert Clock Corporation, Winsted, Conn., a corporation of Connecticut Application January 22, 1953, Serial No. 332,592

3 Claims. (CI. 58-80) This invention relates generally to timepieces of the stem-setting type, and more particularly to the time trains of timepieces of this type.

In many electric or non-electric timepieces the driving and driven parts of the usual minute-wheel end assembly are in frictional driving engagement with each other, so that the minute and hour hands may slip the friction between these parts and be turned for time-setting purposes on meshing the pinion on the set stem with the usual dial wheel assembly and turning the usual knob on the set stem.

It is an object of the present invention to provide in the time train of a timepiece of this type between the driving and driven parts of the usual minute-wheel end assembly thereof a friction coupling that resists slippage between these parts with a force which is noticeably larger when the hands of the timepiece are either normally advanced by the time train or manually set in counterclockwise direction than when they are set in clockwise direction, thereby to offer an unmistakable inducement to set the hands with ease and rapidity in the prescribed clockwise direction and with minimum re action on the normal drive of the time train by the prime mover of the timepiece.

It is another object of the present invention to provide the aforementioned friction coupling between the driving and driven parts of the minute-wheel end assembly of a timepiece of this type by forcing these parts into frictional driving engagement with each other by means of a helical compression spring of which one end is anchored to and turns with one of the parts and one or more turns, at the other end resiliently bear against the other part and extend in spiral fashion thereon about the common rotary axis of the parts, so that the friction between the spring and the part resiliently engaged thereby tends to contract the spring spiral, and consequently increase the compression of the spring, when the hands of the timepiece are either normally advanced by the time train or manually set in counterclockwise direction, and this same friction tends to expand the spring spiral, and consequently relieve the compression of the spring, when the hands of the timepiece are set in clockwise direction.

It is a further object of the present invention to arrange the aforementioned coupling spring so that the spirally extending turn or turns thereof which bear against one 7 of the coupled parts gradually recede from, rather than approach, the spring axis, thereby to achieve with a spring of minimum size a maximum coupling effect between the parts of the minute-wheel end assembly of a timepiece of this type.

Another object of the present invention is to have the aforementioned coupling spring in the form of a conical helix which, when anchored with its inner end on one of the coupled parts of the minute-wheel end assembly of a timepiece of this type, is compressed substantially flat against the other part, so that the spring will exert its maximum compressive force on these coupled parts, and will also bear with substantially all of its turns against the adjacent part to achieve not only maximum friction between the latter and the spring but also optimum variation of the force with which the spring resists slippage of the parts under the aforementioned different operating conditions of the hands of the timepiece.

it is still another object of the present invention to provide for ready assembly of the aforementioned parts and coupling spring into a self-contained minute-wheel tatable on the staff 18. The

2,697,324 Patented Dec. 21, 1954 end unit or assembly, 'by simply passing the driving part over an axially extending shank on the driven part and seating it on the latter, and then placing the spring on the seated part in axial alignment therewith and compressing the same until its innermost turn snaps into a peripheral groove in the shank for the secure anchorage of the spring and also for the secure connection of the coupled parts.

Further objects and advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a part-elevational part-sectional view of a movement embodying the present invention;

Fig. 2 is an enlarged section taken on the line 2-2 of Fig. 1, and showing certain prominent parts of the time train of the movement;

Figs. 3 and 4 are fragmentary sections similar to Fig. 2, but showing the aforementioned prominent parts of the time train of the movement under conditions, respectively; and

Fig. 5 of the time train of the movement.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference numeral designates a movement of a timepiece, having a frame consisting of the usual movement plates 12 and 14 which are held inrelation by pillars 16. Suitably journalled spaced parallel with their ends in the movement plurality of statfs 18 and 20. Carried by the staff 18 is an intermediate sweep-wheel assembly 22 comprising two gears 24 and 26 which turn in unison. The gear plates 12 and 14 are a 24 is drivingly connected through additional gearing (not shown) with the prime mover of the movement which may be an electric motor in the case of an electric clock or a main spring or weight in the case of a non-electric clock. The gear 26 is in permanent mesh with a gear wheel 28 of a sweep-wheel end assembly 30 which further comprises a pinion 32 that turns with the gear wheel 28. The sweep-wheel end assembly 30 is mounted on an arbor 34 which in this instance carries a sweep second hand 36 and advances the same clockwise through one revolution during 60 seconds or one minute.

Meshing with the pinion 32 is a gear wheel 38 of an intermediate minute-wheel assembly 40 which further comprises a pinion 42 that turns with the gear wheel 38. The intermediate minute-wheel assembly 40 is freely ropinion 42 is in permanent mesh with the driving gear wheel 44 of a minute-wheel end assembly 46 which further comprises a driven gear wheel 48 on an arbor 50 that carries a minute hand 52 and is nested between the sweep second hand arbor 34 and an hour-hand arbor 54. The gear wheels 44 and 48 of the minute-wheel end assembly 46 are frictionally drivingly connected by a coupling spring 56 in a manner described hereinafter. The time train described so far advances the minute hand 52 clockwise through one revolution during each hour.

Meshing with the gear wheel 48 is a gear wheel 58 of a dial wheel assembly 60 which has also a gear wheel 62. The dial wheel assembly 60 is carried by the statf 20, and its gear wheel 62 is in permanent mesh with a gear wheel 64 on the before-mentioned arbor 54 which carries an hour hand 66. The time train of the movement is now complete, and the same normally advances the hour hand 66 clockwise through one-twelfth of one revolution during each hour. The instant time train is, with the exception of the coupling spring 56, entirely conventional and forms no part of the present invention.

The instant movement is of the hand-setting type, and is to this end provided with an axially shiftable stem 70 carrying a pinion 72 that may be brought into and from meshing engagement with the gear wheel 58 of the dial wheel assembly 60. In order to set the hands of the movement, the stem 70 is manually shifted from its normally retracted position (not shown) into the position shown in Fig. l

the gear wheel 58, whereupon the stem 70 is manually different operating 18 a side view of a disassembled prominent part in which the pinion 72 is in mesh with turned, conveniently by means of the usual knob provided thereon" for that purpose. In thus turning the stem 70, the minute and hour hands 52 and 66, respectively, will be turned independently of the time train of the movement in either direction, depending on the direction of rotation of the stem 70. When thus turning the stem 70-however, the gear wheel 48 of the minute-wheel end assembly 46 will slip the friction between it and the gear wheel 44- and thus permit the setting of the hands, as described, without undue interference with the normal drive by the prime mover of the movement of that part of the time train which is not involved in setting the hands. v a

In accordance with the present invention, the coupling spring 56 is constructed and arranged to achieve the frictional drive between the gear wheels 44 and 48 of the minute-wheel end assembly 46. To this end, the spring 56, which is helical, is axially compressed in order to hold the face 74 of the gear wheel 44 in frictional driving engagement with the face or shoulder 76 of the gearv wheel 48. More particularly, the gear wheel 48 isprovided, with an axial shank 78 on which "the gear wheel 44 isrotatable and also axially slidable into and from face-to-face engagement with the gear wheel 48, and

the shank 78 is provided with a peripheral groove 80 in.

which one end of the spring 56 is anchored and held in the axially compressed condition shown in Fig. l in which the same holds the gear wheels 44 and 48 in frictional driving engagement.

,The spring 56is preferably of the conical helix type, assuminga shape like or similar to that shown in Fig; when disassembled from the time train of the movement and more particularly from the minute-wheel end assembly 46. Conveniently, the spring 56 is anchored on the shank 78 of the gear wheel 48 by having its innermost turn or convolution 84 received in the peripheral groove 80 in the shank 78. Furthermore, the peripheral groove 80 in the shank 78 .is located in such close proximity to the gear wheel 48 that .the, spring 56 is in its anchored condition preferably axially compressed into nearly flat disposition so that all turns of the spring, except the anchored innermost turn 84 thereof, bear against the. adjacent face 86 of the gear wheel 44. ing the spring 56 in nearly flattened condition, its maximum compression is utilized in holding the gear wheels 44 and 48 infrictionaldriving engagement which will securely hold and transmit the normal drive of the time train from the gear wheel 44 to the gearwheel 43, yet will permit slippage between these gear wheels when the hands ofthe movement are manually set in the previously described manner,

ln accordancewith an nnportant aspectrof the present invention, the spring 56 is so wound directionally that the turns thereof, which in the axially compressed condition of the spring bear against the gear wheel 44, tend to contract when the gear wheel 44 is the driver and transmits the drive of the time train to the gear wheel 48 in the normal operation of the movement. This tendency ofthe turns of the spring52 to contract in normal operation of the movement is highly advantageous in that even minute contraction of these spring turns results in increased compression of the spring and, accordingly,,binds the spring more firmly to the gear wheel 44. However, in order that the spring turns may in the normal operation of the movement tend to contract as mentioned, the anchorage of the spring on the shank 78 must be such that the spring will turn with the gear wheel 48 if the same is turned against and relative to the gear wheel 44. To this end, the innermost turn 84 of the spring 56 is received in the peripheral groove 80 in the shank 78 with sufiicient snugness' to couple the spring to. the shank 78 for unitary rotation therewith even when the. gear, wheel 48 is turned against and relative to the gear wheel 44.

The reason for the spring turns tendency to contract in normal operation of the movement lies in the friction between the face 86 of the gear wheel 44 and the spring turns bearing there'against. of the movement the driving gear wheel 44 turns in the direction of the arrow 90 in'Fig. 2, and since both, the engaged wheel faces 74 and 76 and the springs engagement with'the wheel face 86, transmit the drive of the gear wheel 44 to the gear wheel 48, it stands to reason that the friction encountered by the spring '56 .on the .a'diacent'face 86 of the :gear wheel 44 tends to and-will Thus, -in normal operation,

In thus holdslightly contract the spiral turns of the spring in the manner shown exaggerated in Fig." 3. As the movement stops, the spiral turns of the spring 56 will recover their original shape (Fig. 2). Accordingly, the spring 56 will exert its maximum compression on the gear wheel 44 and will become most firmly bound thereto when the other gear wheel 48 of the minute-wheel end assembly 46 is driven by the time train of the movement.

The same frictional reaction on the spiral turns of the spring 56 that results in maximum compression of the same against the gear wheel 44, will obtain when the hands of the movement are set in counterclockwise direction. In that case, the spring 56, which turns with the gear wheel 48 as explained, will drag on the face 86 of the gear wheel 44 in clockwise direction as viewed in Fig. 2, with the result that the friction which the spring encounters on the gear wheel 44 tends to and will contract the spiral turns of the spring (Fig. 3). Hence, counterclockwise setting of the hands of the movement is resisted with the maximum force of the spring 56.

It is aunique feature of the instant coupling spring 56 that the same permits setting of the hands of the movement in the prescribed clockwise direction with considerably less effort than is required in setting the hands in counterclockwise direction. Thus, in setting the hands of the movement in clockwise direction, the spring 56 will drag on the face 86 of the gear wheel 44 in counterclockwise direction as viewed in Fig. 2, with the result that the friction which the spring encounters on the gear wheel, 44 tends to and will expand the spiral turns of the spring in the manner shown exaggerated in Fig. 4, Expansion of the spiral turns of the spring 56 will, of course, result in decreased compression of the same, wherefore less effort is involved in slipping the friction between the parts of the minute-wheel end assembly 46.

The difference in the resistance encountered in setting the hands of the movement in clockwise and counterclockwise directions is quite noticeable and offers an unmistakable inducement to set the hands of the movement in the prescribed clockwise direction with ease and rapidity and with the least reaction on the normal drive of the time trainby the prime mover of the timepiece.

The instant coupling spring 56 also affords quickand easy assembly of the parts of the minute-wheel end assembly 46. To this end, the gear wheel 44 is passed over the shank 78 of the gear wheel 48, whereupon the spring 56 is placed over the shank 78 and simply compressed until the innermost turn 84 of the spring snaps into secure anchorage in the peripheral groove 80 in the shank 73. p

While in the example shown and described the spring 56 is anchored to the driven gear wheel 48 and bears against the driving gear wheel 44, it is obviously within the purview of the present invention to have the spring anchored to the driving gear wheel 44 and bear against the driven gear wheel 43. in that case, the spring would ,be anchored to an axial shank on the driving gear wheel 44 on which the gear wheel 48 would be rotatable and axially slidable, and the spiral turns of the spring would bear against the adjacent face of the gear wheel 48, with the spring turns directed to achieve their desired con-' traction during normal operation of the movement or when setting the hands in counterclockwise direction, and to achieve their desired expansion when setting the hands in the prescribed clockwise direction.

insofar as the underlying principle of the present in-" vention, i. e. the contraction and expansion of the spiral turns of the spring under the explained different operating conditions of the time train of the movement, is concerned, the same may be attained without necessarily anchoring the spring to the gear 48 for rotation therewith. Thus, the objective of contraction and expansion of the spiral turns of the spring under the ex pia'ined different operating conditions of the time train of the movement may be attained by anchoring the innermost turnof thercompressed spring to a fixed sup port. so that the spring may not turn with either one of the wheelsof the minute-wheel end assembly. How ever, the previously described anchorage of the inner most turn of the spring to one of the wheels of the minute-wheel end assembly is far preferred because the spring will turn with the wheels of this assembly during 'norrnal operation of the movement and the fric,-

tional wear of the parts of the assembly will, accordingly, be kept at a minimum.

The invention may be carried out in other specific ways than those herein set forth Without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range f the appended claims are intended to be embraced theren.

What is claimed is:

1. A one-way drive for a timepiece, comprising two independently coaxially rotatable wheels of which one wheel is axially movable with one face into and from engagement with the adjacent face of the other wheel; and an axially compressed helical spring for resiliently holding said one wheel in frictional face-to-face engagement with said other wheel, said spring having one end anchored against rotation with said one wheel and having at its other end a turn bearing against the other face of said one wheel and extending spirally about the rotary axis of said wheels so that said spiral spring turn tends to contract and expand and, hence, frictionally drivingly connect and disconnect said wheels on turning either wheel in opposite directions, respectively, relative to the other wheel when the latter is connected with a load of a certain magnitude.

2. A one-way drive for a timepiece, comprising two wheels of which one wheel has an axial shank on which the other wheel is rotatable coaxially of said one wheel and axially slidable with one face into and from engagement with the adjacent face of said one wheel; and an axially compressed helical spring for resiliently holding said other wheel in frictional face-to-face engagement with said one wheel, said spring surrounding said shank and having one end anchored thereto for rotation with said one wheel, and having at its other end a turn bearing against the other face of said other wheel and extending spirally about the common rotary axis of said wheels so that said spiral spring turn will tend to contract and expand and, hence, frictionally drivingly connect and disconnect said wheels on turning either wheel in opposite directions, respectively, relative to the other wheel when the latter is connected with a load of a certain magnitude.

3. A one-way drive for a timepiece as set forth in claim 2, in which said spring is a conical helix having a plurality of turns and being anchored at its innermost turn to said shank in axially compressed condition in which the majority of said turns bear against said other face of said other wheel.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,375,348 Balch Apr. 19. 1921 1,442,417 Truebe Jan. 16, 1923 1,940,880 Pitter Dec. 26. 1933 2,061,827 Brooks Nov. 24, 1936 

